In HC white matter, activated NF-κB p65 was found in microglial nuclei, while the c-Rel and p50 subunits and IκBα were restricted to the cytoplasm; in MS active lesions, p65, p50, and IκBα were all present in macrophage nuclei; some hypertrophic astrocytes exhibited nuclear NF-κB p65; perivascular lymphocytes showed nuclear localization of c-Rel. This evidence concerns the gene REL and myeloid sarcoma.